The way to mod Mass Effect 3 has moved from releasing game-file-changing *.mod files to releasing mods in the form of DLC. It is still a fairly intensive process that really needs to be much more automated (the way making *.mod files was) but it is definitely a better format. You can change the game without actually changing the game, so to speak. No more changing game pcc files from the original, just download the DLC zip file, unzip it into your game DLC folder, a quick update of the game PCConsoleToc.bin file, and you are off and running the new mod. Decide to drop the mod? Simply remove the mod's DLC folder. You don't have to repair your game install or reinstall from scratch anymore.
The downside is the hair-pulling, cussing, and banging of your head on your desk when you screw up some aspect of the texturing process and have to start over from scratch on creating the mod. After a few weeks of this I finally got my first DLC mod version out and, like my first mods for the game (the first mesh mods for ME3 ever) were Ashley. They are my most extensive as far as number of changes made, though not the most drastic (that would be my Tali full-face mod is the most extensive and difficult I did - following from what I learned doing that, I made my EDI new look mod). She is my favorite female in the series, an avatar for my dream woman, so she got most of my attention. The mod I released currently includes all my Ashley mods plus some additional mods for other characters (full clear face helmet mod for all others, including Liara, new armor for Ash and Liara). Because a few of the modded files required to do Ashley ALSO include other characters I've modded (EDI, Liara) I will be expanding the DLC over time to include those mods as well. It will still mostly be Ashley Plus though.
I'll release Tali and nude Traynor (showers, romance scene) as separate smallish DLC.